Question

Steroid hormones are secreted by a. the adrenal cortex. b. the gonads. c. the thyroid. d. both \(a\) and \(b\). e. both \(b\) and \(c\).

Short answer

Option D: both \(A\) (the adrenal cortex) and \(B\) (the gonads) secrete steroid hormones.

Step-by-step solution

Option A: Adrenal Cortex

The adrenal cortex is a part of the adrenal gland and is responsible for producing various steroid hormones such as cortisol, aldosterone, and androgens.

Option B: Gonads

Gonads are the primary reproductive organs, and they include the ovaries in females and testes in males. These organs produce sex hormones, which are steroid hormones. In females, the ovaries primarily secrete estrogen and progesterone, while in males, the testes produce testosterone.

Option C: Thyroid

The thyroid gland produces and secretes hormones called thyroxine (T4) and triiodothyronine (T3), which help regulate metabolism. These hormones are not classified as steroid hormones but are instead classified as amino acid-derived hormones.

Option D: Both A and B

As described above, both the adrenal cortex (Option A) and gonads (Option B) are involved in the production and secretion of steroid hormones.

Option E: Both B and C

Although the gonads (Option B) produce steroid hormones, the thyroid gland (Option C) does not. Therefore, this option is not correct. Based on the information above, the correct answer is:

Answer

Option D: both A (the adrenal cortex) and B (the gonads) secrete steroid hormones.

Key concepts

Steroid Hormones

Steroid hormones are a category of hormones that play critical roles in the body's daily functioning. They are fat-soluble molecules that originate from cholesterol, making them unique in how they enter cells and impact cellular functions.
Steroid hormones can easily pass through cell membranes due to their lipophilic nature. Once inside the cell, these hormones typically bind to specific receptors located in the cell nucleus. This binding triggers changes in gene expression, which ultimately alters the cell's behavior.

• Examples include cortisol, testosterone, estrogen, and progesterone.
• They regulate a variety of functions like metabolism, immune response, and reproduction.

Because of their widespread actions, maintaining a balanced level of steroid hormones is essential for good health.

Adrenal Cortex

The adrenal cortex is the outer section of the adrenal glands, which are located above the kidneys. This part of the adrenal gland is crucial for producing various steroid hormones, which are key to many bodily processes.
The main hormones produced by the adrenal cortex are corticosteroids, including glucocorticoids like cortisol and mineralocorticoids like aldosterone.

• Cortisol helps manage stress, regulates metabolism, and reduces inflammation.
• Aldosterone plays an important role in controlling blood pressure by managing the balance of electrolytes and water in the body.

Additionally, the adrenal cortex also produces small amounts of androgenic steroids, which complement those produced by the gonads.

Gonads

Gonads are specialized reproductive organs found in both male and female bodies, tasked with generating reproductive cells and producing various hormones. In females, gonads refer to the ovaries, while in males, they refer to the testes.
These organs are integral to producing sex hormones, which are crucial steroid hormones involved in reproductive functions and secondary sexual characteristics.

• In females, the ovaries secrete estrogen and progesterone.
• In males, the testes primarily produce testosterone.

These hormones help regulate the menstrual cycle, support pregnancy, influence the development of male characteristics, and govern libido, showcasing the diverse roles of gonadal hormones.

Thyroid Gland

The thyroid gland is a butterfly-shaped gland situated in the neck, which plays a vital role in regulating metabolism. Despite being a significant part of the endocrine system, its hormones differ from steroid hormones.
The thyroid gland produces thyroxine (T4) and triiodothyronine (T3), both of which are amino acid-derived hormones rather than steroid hormones.

• These hormones control the rate at which the body uses energy, affecting weight, heart rate, and temperature.
• Proper thyroid hormone levels are critical for normal growth and brain development, especially in children.

The activities of the thyroid gland highlight the diverse nature of endocrine organs and the range of hormones they produce, distinct from those produced by the adrenal cortex and gonads.